Portable power bank



FIG. 1 is a top view of a portable power bank showing my new design;

FIG. 2 is a bottom view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a left side view thereof;

FIG. S is a front view thereof;

FIG. 6 is a rear view thereof;

FIG. 7 is a top, rear, right side perspective view thereof; and,

FIG. 8 is a top, front, left side perspective view thereof.

The broken lines shown in the drawings illustrate portions of the portable power bank that form no part of the claimed design. 

CLAIM The ornamental design for a portable power bank, as shown and described. 